U.S. Bancorp agreed Monday to buy investment company Piper Jaffray Companies Inc. for $730 million, ending months of speculation that started shortly after Piper finished cleaning up the fallout from a disastrous derivatives-based investing strategy.

The company spent more than $100 million settling lawsuits resulting from the failed derivatives strategy. The century-old investment banking and brokerage concern had been mentioned as a can-didate for acquisition for several months.